Feline demodicosis is a parasitic condition affecting the skin of cats. To date two species of mites have been described, Demodex cati and Demodex gatoi. A third unnamed species that differs morphologically from the others has also been observed. Demodex cati are considered normal fauna and are rarely associated with disease in cats with compromised immunity. Unlike D. cati, D. gatoi is believed to be a contagious parasite that can be transmitted among cats and possibly other species. Infestation with D. gatoi causes an extremely itchy (pruritic) skin disease in otherwise healthy cats. Diagnosis of D. gatoi requires the detection of mites, currently performed using a skin scraping technique. Because few mites may be needed for the development of clinical signs, this technique is insensitive and a negative result is uninterpretable. Therefore, a diagnosis may only be reached when cats' pruritus responds to treatment. This is problematic since the only effective treatment for D. gatoi infestation in cats is weekly dips with lime sulfur for a minimum of six weeks. It is recommended that all cats in a household be treated when D. gatoi is suspected. Because of the difficulty in diagnosing this disease with current technology and the difficulty and inconvenience of multiple cat dips, especially when diagnosis may be uncertain, a more sensitive and accurate test is highly desirable. Molecular methods of diagnosis, such as the polymerase chain reaction, have greatly improved diagnosis of infections. Molecular diagnostic approaches have not been possible for D. gatoi because no DNA sequence information has been available for feline mites.
Thus additional methods are need for the diagnosis of discrimination between Demodex cati and Demodex gatoi. This disclosure meets those needs.